Very nice! Really enjoyed it!
The age mechanic was really nice. Having to wait for the time to run out to grow older is kind of annoying sometimes, but it actually fits the theme of the game so it doesn't bother me that much.
The music was good, but a bit repetitive! Maybe it would be better if it didn't repeat after every stage, so it doesn't feel like you're hearing the first 5-10 seconds all the time.
The powers for each character are well chosen, being thematically and mechanically appropriate. However, the implementation of the adult punch is kind of weird. I wish you could punch enemies from further away... I had to position myself in a really specific place. Too far away and I wouldn't hit the enemy, too close and I would die... there should really be more range to the attack!
The level design is generally OK, but there is this one level in the middle of the game that completely threw me off. It's a level inside the house, and it's the one that makes you go all the way to the right as an elder, go down a bit, punch an enemy as aduly, go all the way to the left, crawl under some spikes as baby, go down a bit and then go all the way right as an adult. At the beginning, you need to be really quick to reach the clock in time before you die. It's doable, but it makes the level a lot more difficult than the ones after it. Then at the bottom there's this one jump which is almost impossible, where you need to jump over a pit with four spikes. This is an almost pixel-perfect jump! I think three spikes would have been enough. It's not a particularly interesting jump (you don't have to make use of the main mechanic at all to go through, it's pure mechanical skill... or maybe I missed something), so the difficulty of this one jump is kind of off-putting. Actually, this level was so much harder than the ones before that I actually thought it would be the final level! I was super surprised to see this level followed by much, MUCH easier (and shorter!) levels. I don't know if you could reskin this level to fit the end of the game better, but it would be much better as the last level.
Speaking of the end, it's kind of depressing that you get a screen saying "You win!" and all you can do is watch the clock run out repeatedly... But that was the tone you were going for, so in that regard you succeeded.
Overall it's a very solid game, despite me complaining about everything. It's certainly one of my highest rated here! And it's one of the most memorable, too. Good job :)